Schroeder tracks the end of innocence in much the same way that the strip captured it each time out. Unlike "Salinger," he hardly makes a spectacle out of Watterson's secluded tendencies. The pileup of interview subjects speak eloquently on his behalf.

The film, named for "Calvin" creator Bill Watterson, offers not only an in-depth look at the comic strip's unique influence but also a concise snapshot of the dwindling state of newspapers and their "funny pages."

The deeply private, intensely ideological and undeniably brilliant Watterson would make an absolutely fascinating subject. But director Joel Allen Schroeder has no access to him. So instead he talks a lot about how much he loves “Calvin and Hobbes” and then invites other fans to do the same.

Look, Dear Mr. Watterson is a nice movie. Calvin & Hobbes fans may get a kick out of it. But it falls squarely into the promotional genre of documentary filmmaking — the same way so many music docs nowadays seem to be just movies about how awesome the director’s favorite band is.

The documentary is at its best when it eases up on the adoration a little and turns to a serious discussion of the state of comics these days, what with newspapers on the decline and digital media scattering an art form that was once centralized on pages delivered to everyone's door.

So, be warned: You may not learn anything from this mild, unremarkable film, but you might be tempted to order the deluxe, four-volume “The Complete Calvin and Hobbes” after watching it. I was, and I don’t regret it a bit.

Schroeder isn’t much of a comic-strip expert or historian, by his own admission, so Dear Mr. Watterson bounces off many of the most interesting issues in and around “Calvin and Hobbes,” noticing them but not exploring them deeply.

Just as it’s impossible to capture in a 600-word review what made Calvin And Hobbes so special, no 100-minute film on the subject can really hope to convey its magic either. But Dear Mr. Watterson does its best, relying on choice excerpts of the work and enthusiastic talking-head interviews.

For all its fandom and self-indulgence, Dear Mr. Watterson does offer some insightful musings about the decline of comic strips in general, with their content ever shrinking due to the diminished state of the newspaper industry.

But viewers looking to learn more about Mr. Watterson and his creation than what’s contained in his Wikipedia entry may come away as hopped-up with impatience as Calvin when confronted by parental indifference.